Field of the Invention
The present invention relates to a pulse laser and photoacoustic apparatus configured to emit light pulses repetitiously.
Description of the Related Art
Photoacoustic apparatuses that emit light from a pulse laser onto a subject and use a probe to receive photoacoustic waves generated from inside the subject, to obtain information on the form and function of the interior of the subject are widely researched in the medical field. When applying such a photoacoustic apparatus to biological subjects, the intensity of the light irradiated onto the biological subject must be controlled so as to not be more than a pre-determined safe threshold. This threshold is known as the maximum permissible exposure (MPE). The intensity of light emitted from such a pulse laser may be controlled depending on the objective.
Japanese Patent Laid-Open No. 63-153875 discloses an example of a method to control the intensity of light emitted from a pulse laser. Japanese Patent Laid-Open No. 63-153875 discloses a method in which current flowing to a lamp for exciting a laser medium and the voltage applied to this lamp is detected to obtain a value for the power input to the lamp. Japanese Patent Laid-Open No. 63-153875 discloses a method to control the power value next input to the lamp so that this value stays within a predetermined range on the basis of the obtained power value.